I hold that the mark of a genuine idea is that its possibility can be proved, either a priori by conceiving its cause or reason, or a posteriori when experience teaches us that it is in fact in nature.

We live in the best of all possible worlds

I also take it as granted that every created thing, and consequently the created monad also, is subject to change, and indeed that this change is continual in each one.

He who understands Archimedes and Apollonius will admire less the achievements of the foremost men of later times.

I am convinced that the unwritten knowledge scattered among men of different callings surpasses in quantity and in importance anything we find in books, and that the greater part of our wealth has yet to be recorded.

If we were magically shrunk and put into someone's brain while she was thinking, we would see all the pumps, pistons, gears and levers working away and we would be able to describe the workings completely, in mechanical terms, thereby completely describing the thought processes of the brain. But that description would not contain any mention of thought! It would contain nothing but descriptions of pumps, pistons, levers!

Music is a secret and unconscious mathematical problem of the soul.